The central importance of the cellular immune system in controlling mycotic disease has been supported by a large body of animal experimental data but relatively little work has addressed human defense mechanisms and their clinical significance. The major goal of this proposal is to investigate the role of human effector lymphocytes --natural killer (NK) and lymphokine- activated (LAK) cells and antigen-specific cytotoxic T-cells--in innate and acquired immunity to pathogenic fungi. The lytic reactions mediated by these cells will be studied in vitro against Blastomyces dermatitidis and related fungi. A rigorous five-year training program is proposed which combines course- and bench-work in cellular and molecular immunology, medical mycology, fungal and yeast genetics, biochemistry and molecular biology, and related experimental techniques. The experimental system will be developed in the first three years of the program. Research projects will involve assays of cell- mediated lympholysis of B. dermatitidis (and related fungi), using both nonspecific effector cells (NK and LAK cells) and antigen- specific effector cells (antigen-stimulated lymphocytes from previously infected, immune donors) to lyse fungal targets. Blastomyces alkali- and water-soluble antigen will be used to study the antigen-specific T-cell response to B. dermatitidis. Effector cell-fungal interactions, effector cell properties, and fungal antigen determinants that elicit a cytotoxic response will be characterized. In the last two years of the program, effector cell clones will be used to study effector cells, cell-surface structures that recognize and bind fungi, fungal cell wall molecules, and genetic control of effector-target interactions. Results of in vitro assays will also be correlated with disease manifestations in humans. This program will provide excellent scientific training for the candidate and will contribute to knowledge about the immunobiology of human lymphocytes and the cellular and molecular mechanisms by which these cells control mycotic disease. This knowledge in turn will facilitate rational and innovative strategies for prevention and immunotherapy of mycotic disease.